Effects of Material Parameter Variability on Buckling and Creep Fatigue Interaction at Elevated Temperature

1976 ◽  
Vol 98 (1) ◽  
pp. 75-80 ◽  
Author(s):  
I. Berman ◽  
A. C. Gangadharan ◽  
G. H. Jaisingh ◽  
G. D. Gupta
Keyword(s):  
Cylindrical Shell ◽  
Fatigue Damage ◽  
Initial Imperfection ◽  
External Pressure ◽  
304 Stainless Steel ◽  
Thin Cylindrical Shell ◽  
Elastic Plastic ◽  
Creep Buckling ◽  
Creep Fatigue ◽  
Type 304

The effects of variation of elastic-plastic and creep properties of type 304 stainless steel on solutions of two specific inelastic problems are studied in this paper. The problems considered are: 1 – elastic-plastic-creep buckling of a thin cylindrical shell with initial imperfection and sustained external pressure at high temperature; and 2 – creep and fatigue damage in a thin cylindrical shell subjected to cyclic thermal load and constant internal pressure. Some conclusions are drawn as to the relative importance of variations of different material parameters on initial buckling load, creep buckling time and creep and fatigue damage factors.

A Parametric Study of Elastic-Plastic-Creep Buckling of a Thin Cylindrical Shell

1974 ◽  
Vol 96 (3) ◽  
pp. 155-161 ◽  
Author(s):  
I. Berman ◽  
J. M. Chern ◽  
G. D. Gupta
Keyword(s):  
Cylindrical Shell ◽  
External Pressure ◽  
Buckling Load ◽  
Sustained Load ◽  
Thin Cylindrical Shell ◽  
Elastic Plastic ◽  
Creep Buckling ◽  
Explicit Reference ◽  
Class 1 ◽  
Plastic Creep

The elastic-plastic-creep buckling of a long thin cylindrical shell with initial out-of-roundness subjected to uniform external pressure is herein studied. The work is carried out by means of an economical computer program which consistently accounts for the effects of load changes and plastic strains and which has a calculation procedure based on direct integration. The ratio of the sustained load to the initial buckling load is discovered to be a parameter which relates the sustained load to the buckling time without explicit reference to the geometric parameters for the conditions considered. Other results are uncovered concerning the effect of: the shape of the imperfection, the temperature variations and the choice of creep relations on initial buckling load and buckling time. Alternatives to the expensive and time consuming calculations to meet the requirements of the time factor of safety on Code Case 1331 of the ASME Boiler and Pressure Vessel Code for Class 1 nuclear components are explored. Recommendations are made.

Visualization of Thermal Fatigue Damage Distribution With Elastic-Plastic FEA

2018 ◽  
Author(s):  
Junya Miura ◽  
Terutaka Fujioka ◽  
Yasuhiro Shindo
Keyword(s):  
Fatigue Damage ◽  
Thermal Fatigue ◽  
Thermal Loading ◽  
304 Stainless Steel ◽  
Element Analysis ◽  
Steel Cylinder ◽  
Elastic Plastic ◽  
Calculation Results ◽  
Type 304 ◽  
Cae System

This paper proposes simplified methods to evaluate fatigue damage in a component subjected to cyclic thermal loading, in order to visualize the distribution of usage factor using a graphical user interface (GUI) incorporated in a widely-used commercial CAE. The objective is to perform the evaluation and visualization using a standard desktop PC. In the previous paper, three simplified methods based on elastic finite-element analysis (FEA) were proposed in place of the method in the procedures employed in ASME Section III Subsection NH. In this paper, the methods have been improved for elastic-plastic FEA. A previously performed thermal fatigue test with a type 304 stainless steel cylinder was simulated. Heat transfer, elastic, and inelastic analyses were conducted. Simultaneously with the analyses performed, the equivalent total strain ranges and fatigue usage factor distributions were calculated using user subroutines developed in this study including three newly proposed simplified and ASME NH-based methods. These distributions can be visualized on a GUI incorporated in a commercial FEA code. The calculation results were consistent with the distribution of cracks observed. In addition, by using these, the analysts can visualize these distributions using their familiar CAE system.

Creep Buckling Under Varying Loads

1991 ◽  
Vol 113 (1) ◽  
pp. 41-45 ◽  
Author(s):  
N. Miyazaki ◽  
S. Hagihara ◽  
T. Munakata
Keyword(s):  
Cylindrical Shell ◽  
Spherical Shell ◽  
Circular Cylindrical Shell ◽  
Critical Time ◽  
Initial Imperfection ◽  
External Pressure ◽  
Deformation Analysis ◽  
The Finite Element Method ◽  
Creep Buckling ◽  
Damage Rule

Creep buckling analyses under stepwise varying loads are performed on a circular cylindrical shell with initial imperfection subjected to axial compression and a partial spherical shell under uniform external pressure. The finite element method is applied to a creep deformation analysis to obtain the critical time when creep buckling occurs. The results show that a linear cumulative damage rule for creep buckling can be well applied to the creep buckling of the circular cylindrical shell, but cannot to that of the partial spherical shell.

Relationship of Creep, Creep-Fatigue, and Cavitation Damage in Type 304 Austenitic Stainless Steel

1989 ◽  
Vol 111 (2) ◽  
pp. 123-131 ◽  
Author(s):  
Saurin Majumdar
Keyword(s):  
Stainless Steel ◽  
Hold Time ◽  
Strain Range ◽  
304 Stainless Steel ◽  
Growth Equation ◽  
Full Potential ◽  
Basic Study ◽  
Cavitation Damage ◽  
Creep Fatigue ◽  
Type 304

Available creep and creep-fatigue data on type 304 stainless steel are re-examined in the light of recently generated basic cavitation data on the same material. This basic study has shown creep damage to be a highly inhomogeneous phenomenon, both in space and in time. A small fraction of boundaries are so intensely cavitated by about 10–25 percent of life that for all practical purposes they can be considered cracked. Other similar boundaries, that are similarly oriented with respect to the tensile stress direction, however, are almost devoid of cavities at the end of life. The early nucleation of cracks by creep mechanism has a significant influence on creep-fatigue interactions, particularly for tests at low strain ranges. A simple ductility exhaustion model appears to be able to account for the early crack initiation. A hardness-modified ductility approach appears to provide an upper bound to the ductility displayed by all tests and correlates data for long hold-time fatigue tests at low strain range. Tests at higher strain ranges and/or shorter hold times do not achieve their full potential ductility because their lives are cut short by crack propagation. Their lives can be predicted empirically by an enhanced fatigue crack growth equation in the presence of cavitation damage.

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